PTCA procedures generally include inflation of a balloon in an arterial passage in an effort to clear a flow path for blood by dilating the stenosis. Inflation of the balloon and subsequent deflation and removal of the balloon results in treatment of the stenosis to increase the available cross-sectional area for blood to flow through the arterial passage.
In typical PTCA procedures, a guiding catheter is inserted into the cardiovascular system through the Tee-brachial or femoral arteries, generally under local anesthesia, until the distal tip of the catheter is in a coronary artery and generally positioned adjacent a stenosis. An extensible balloon of a dilation catheter is advanced through the guiding catheter alone or over a previously introduced guidewire until the balloon is positioned across the stenosis. The balloon is then inflated to a predetermined size with a fluid, preferably a radiopaque liquid, to radially compress the inside of the artery wall, thereby dilating the lumen of the artery. The balloon is then deflated so that the dilation catheter can be removed, and blood flow resumed through the dilated artery that now has a larger cross-sectional area to permit a greater volume of blood to flow therethrough.
In typical PTCA procedures, when the balloon of a dilation catheter is inflated in a coronary artery, all flow ceases through the coronary artery. If blood flow ceases for too long a period of time, the part of the heart which that coronary artery serves can begin to suffer from lack of blood, or ischemia. If the balloon remains inflated in the artery for prolonged periods of time, the injury caused by the absence of blood flow can be irreversible in some cases. On the other hand, it has been found that the probability of an artery wall or the stenosis maintaining its dilated cross-sectional area after having been subjected to dilation from an extensible balloon is directly related to the length of time that the balloon is inflated while located across the stenosis. However, the aforementioned potential problems associated with blocking blood flow are increased the longer the balloon is inflated in the artery.
Attempts have been made to produce dilation catheters that perfuse blood through a catheter or balloon when the balloon is inflated to avoid ischemia conditions distally of the balloon. For example, Wejay, et al., U.S. Pat. No. 5,158,540, disclose a perfusion catheter that perfuses blood during the balloon's inflation cycle to allow for longer inflation periods; however, the catheter is extremely complicated structurally and expensive to manufacture.
It is, therefore a general object of the present invention, to provide a new and improved perfusion balloon dilation catheter suitable for PTCA procedures.
Another object of the invention is to provide a dilation catheter suitable for PTCA procedures wherein the catheter perfuses blood around the inflated balloon and permits prolonged inflation times for the balloon.
Yet another object of the present invention is to provide a dilation catheter of a relatively simple structure for use in PTCA procedures where blood is perfused distally of the inflated balloon.
The present invention overcomes the problems associated with the prior art perfusion catheters by providing a perfusion balloon catheter having an annularly shaped extensible balloon including an exterior member and an interior member and an inner longitudinal passageway. The interior member and exterior member are sealingly connected along their edges to define an annular compartment. Also provided is an elongated flexible tubular member having a distal portion disposed in the annular compartment. A pathway is provided between the flexible tubular member and the annular compartment to radially expand the annular balloon so that the exterior member is capable of engaging a body vessel wall while blood is simultaneously perfused through the inner longitudinal passageway.
For a complete understanding of the present invention, reference is made to the embodiments illustrated in greater detail in the accompanying drawings and described by way of example. It should be understood that this invention is not limited to the particular embodiments illustrated herein, but is defined by the appended claims.